1. Field of the Invention
The present invention relates to an interchangeable-lens camera having a camera body to which a lens unit is removably attached, a camera body and a method of determining the mounting of a lens.
2. Description of the Related Art
Interchangeable-lens cameras in which a lens unit having an imaging lens is removably attached to a camera body have become widely available. Examples of such an interchangeable-lens camera include, in general, single-lens reflex cameras equipped with a reflecting mirror that reflects light incident on the lens unit to guide the light to the optical viewfinder, and mirrorless interchangeable-lens cameras without a reflecting mirror. In addition, there are known interchangeable-lens cameras that are provided with an imaging element in the camera body and others that are provided with an imaging element in the lens unit.
Japanese Patent Application Laid-Open No. 7-114087 (PTL 1) discloses the configuration of a camera having a camera body with a detachable lens unit. The camera includes a lens detection terminal dedicated to the detection of the lens unit. When the lens unit is not mounted, a pull-up resistor causes the lens detection terminal to be at a high level, and when the lens unit is mounted, the lens detection terminal is connected to a ground terminal in the camera body through the lens unit. A CPU of the camera body detects a change in the level of the lens detection terminal from high to low so as to determine if the lens unit is mounted.